Feeding and Growth

Question 1

Define growth in fish and shellfish.

Answer 1

Change in size of an individual over time, expressed as volume, mass, energy, protein, etc.

Question 2

What is relative growth rate?

Answer 2

Growth rate divided by the size of the fish (dW/dt * W⁻¹).

Question 3

Name three growth models discussed.

Answer 3

Von Bertalanffy, Logistic, Exponential Growth models.

Question 4

What factors affect growth in aquaculture?

Answer 4

Feed intake, internal conditions, environmental factors.

Question 5

How is fish length commonly measured?

Answer 5

Total Length (TL), Standard Length (SL), Fork Length (FL).

Question 6

Why is standard length preferred for fish measurements?

Answer 6

Less impacted by fin damage compared to total length.

Question 7

What shape does the growth curve of fish typically take?

Answer 7

Sigmoid (S-shaped) curve.

Question 8

What are the three phases of a sigmoid growth curve?

Answer 8

Initial exponential growth, decreasing growth post-inflection, plateau at maturity.

Question 9

What is compensatory growth?

Answer 9

Accelerated growth following a period of restricted feeding.

Question 10

What describes growth using absolute, velocity, and relative velocity terms?

Answer 10

Wt, dW/dt, (dW/dt)/W respectively.

Question 11

What is the Von Bertalanffy Growth Equation?

Answer 11

dW/dt = a1W^b - a2W^c, describing growth as a balance of anabolism and catabolism.

Question 12

In Von Bertalanffy model, what is assumed for catabolism?

Answer 12

Catabolism is proportional to body mass (c=1).

Question 13

What is the principle of exponential growth?

Answer 13

Constant relative growth rate over time.

Question 14

How is Specific Growth Rate (SGR) calculated?

Answer 14

SGR = (ln(Wt) - ln(W0)) / t * 100%.

Question 15

What is metabolic body weight in fish?

Answer 15

W^0.8, where W is body weight.

Question 16

What is metabolic growth rate (RGRm)?

Answer 16

(Wt - W0) / Wg^0.8 / t.

Question 17

How does feed ration affect fish growth?

Answer 17

Higher ration increases growth up to a maximum point, then plateaus or declines.

Question 18

What happens if fish are overfed?

Answer 18

Decreased water quality, reduced oxygen, lower feed intake, and hampered growth.

Question 19

Define maintenance ration (Rm).

Answer 19

Feed level at which growth is zero.

Question 20

Define optimal ration (Ropt).

Answer 20

Feed ration that yields maximum feed conversion efficiency.

Question 21

How does temperature affect fish growth?

Answer 21

Optimal temperature maximizes growth; extreme changes cause thermal shock.

Question 22

What effect does low dissolved oxygen have?

Answer 22

Reduces food intake and growth rates in fish.

Question 23

How do environmental factors like NH4+ or NO3- affect growth?

Answer 23

High concentrations inhibit growth beyond a threshold.

Question 24

What is the relationship between food availability and bivalve growth?

Answer 24

Growth depends on ambient food concentration and water flow.

Question 25

Define clearance rate (CR) in bivalves.

Answer 25

Volume of water cleared of suspended particles per unit time.

Question 26

What triggers feeding in bivalves?

Answer 26

Food concentration surpassing a minimum threshold.

Question 27

What is pseudofaeces in bivalves?

Answer 27

Non-ingested material rejected by the animal, packed in mucus.

Question 28

How does particle size affect bivalve feeding?

Answer 28

Particles 3-8 µm are efficiently retained; smaller particles are poorly retained.

Question 29

What influences absorption efficiency in bivalves?

Answer 29

Diet quality (organic content) and particle selection.

Question 30

How does salinity affect bivalves?

Answer 30

Near tolerance limits, valve closure occurs; low salinity reduces filtration and energy intake.

Question 31

What is the impact of high flow rates on bivalves?

Answer 31

Very high speeds inhibit clearance rates and feeding efficiency.

Question 32

Describe plasticity in bivalve feeding physiology.

Answer 32

Adjustments in gill and palp size based on seston quantity and quality.

Question 33

How do bivalves respond to low food environments?

Answer 33

Increase clearance rate and decrease palp area for higher food intake.

Question 34

What is selection efficiency (SE) in bivalves?

Answer 34

Ability to preferentially ingest high-quality organic material.

Question 35

How does temperature influence bivalve feeding?

Answer 35

Temperature affects maximum feeding rates, but responses vary by environment.

Question 36

How does food quality influence bivalve growth?

Answer 36

Higher food quality improves clearance rate, selection efficiency, and absorption efficiency.

Question 37

What is production carrying capacity?

Answer 37

Maximum biomass sustainable without depleting food resources in aquaculture areas.

Question 38

What is ecological carrying capacity?

Answer 38

Maximum aquaculture level without harming natural ecological processes.

Question 39

What is metabolic faecal loss?

Answer 39

Organic material loss during digestion not absorbed by bivalves.

Question 40

What factors affect growth performance classification?

Answer 40

Required factors, harmful factors, and factors with optimal values.